STP876

    Analysis of Local Delaminations and Their Influence on Composite Laminate Behavior

    Published: Jan 1985


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    Abstract

    An equation was derived for the strain-energy release rate, G, associated with local delamination growth from a matrix ply crack. The critical Gc for edge delamination onset in [±25/902]s graphite/epoxy laminates was measured and used in this equation to predict local delamination onset strains in [±25/90n]s, where n = 4, 6, 8 laminates. A simple technique for predicting strain concentrations in the primary load bearing plies near local delaminations was developed. These strain concentrations were responsible for reduced laminate nominal failure strains in laminates containing local delaminations. The influences of edge delamination and matrix crack tip delamination on laminate stiffness and strength were compared.

    Keywords:

    graphite/epoxy materials, delamination, matrix ply cracks, strain concentration, strain-energy release rate, fatigue, composite materials, interlaminar fracture


    Author Information:

    O'Brien, TK
    Structures Laboratory, U.S. Army Research and Technology Laboratories (AVSCOM), NASA Langley Research Center, Hampton, VA


    Paper ID: STP36310S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP36310S


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